Antiferromagnetism and phase transitions in non-centrosymmetric\n UIrSi$_3$ Article Swipe
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· 2018
· Open Access
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· DOI: https://doi.org/10.48550/arxiv.1804.08832
· OA: W4302568094
Magnetization and specific heat measurements on a UIrSi3 single crystal\nreveal Ising-like antiferromagnetism below T$_N$ = 41.7 K with easy\nmagnetization direction along the c-axis of tetragonal structure. The\nantiferromagentic ordering is suppressed by magnetic fields > H$_c$\n({\\mu}$_0$H$_c$ = 7.3 T at 2 K) applied along the c-axis. The first-order\nmetamagnetic transition at H$_c$ exhibits asymmetric hysteresis reflecting a\nslow reentry of the complex ground-state antiferromagnetic structure with\ndecreasing field. The hysteresis narrows with increasing temperature and\nvanishes at 28 K. A second-order metamagnetic transition is observed at higher\ntemperatures. The point of change of the order of transition in the established\nH-T magnetic phase diagram is considered as the tricritical point (at T$_{tc}$\n= 28 K and {\\mu}$_0$H$_{tc}$ = 5.8 T). The modified-Curie-Weiss-law fits of\ntemperature dependence of the a- and c-axis susceptibility provide opposite\nsigns of Weiss temperatures, {\\Theta}$_p^a$ ~ -51 K and {\\Theta}$_p^c$ ~ +38 K,\nrespectively. This result and the small value of {\\mu}$_0$H$_c$ contrasting to\nthe high T$_N$ indicate competing ferromagnetic and antiferromagnetic\ninteractions responsible for the complex antiferromagnetic ground state. The\nsimultaneous electronic-structure calculations focused on the total energy of\nferromagentic and various antiferromagnetic states, the U magnetic moment and\nmagnetocrystalline anisotropy provide results consistent with experimental\nfindings and the suggested physical picture of the system.\n
